The present invention provides a method for stable long term storage of non glycosylated recombinant human G CSF wherein an aqueous acetate or glutamate buffered G CSF composition containing the non glycosylated recombinant human G CSF and sorbitol is cooled to a temperature of 15°C or below to obtain a frozen G CSF composition which frozen composition is then stored in the frozen state and then increased in temperature to a temperature within the range of from 2°C to 8°C for a period of time adjusted to allow the composition to thaw and to obtain a liquid composition having a G CSF content of at least 95% of the G CSF content of the original composition.
